An innovative optics lab design for residency training in ophthalmology

Proper understanding of the optical function of the eye is the foundation of clinical understanding of ophthalmologists. Although teaching principals of optics has always been a part of ophthalmology residency curriculum, it seems that successful strategies other than lecture—based methods are needed to engage students and facilitate the understanding of optical principals. A collaborative team of physicists (optics Ph.D.), ophthalmologists and medical education experts designed an optics lab for ophthalmology residents to help them practically simulate different optical phenomena. The educational course consisted of 4 sessions of 90 min to practice the optical tests using the lab instruments. Each class consisted of 6–9 residents, divided into 3 groups with a fully equipped unit, and two mentors (an optics Ph.D. professor and an ophthalmology professor). A quasi-experimental design with pre-post test was used to evaluate the effectiveness of the training workshop in changing the ophthalmology residents’ optical knowledge and attitude. Thirty-five residents participated in the study. The average score of residents' performance before the workshop was 5.21 (out of 100), which increased significantly to 66.1 after the workshop. Also, the average knowledge of residents, which was measured as self-reported, increased significantly from 28.85 to 71.09. The average score of students' attitudes and interest was increased from 40.49 to 74.81. It seems that training workshops and labs are effective to bring about change in knowledge and attitude of ophthalmology residents toward optics as a new teaching strategy that would be implemented in their curriculum.

IOL slightly decentered, prescribing eyeglasses with wrong pupillary distance, effect of damaging iris sphincter on depth of field and depth of focus).
Then, a suitable place which we call "optics lab" was equipped with the support of Iranian Society of Physics in Farabi Eye Hospital affiliated to Tehran University of Medical Sciences (TUMS).
For this course, we scheduled 4 sessions for each group of residents (6-9 students) to follow the agenda in three different subgroups (at most 3 residents) with a complete set up, under supervision of optics and ophthalmology professors.Each session started with a quick review of the optical principles which are supposed to be practically simulated in that session by a physic-optics professor.Then, residents practice the designed optics tests, and after each optics test, potential clinical applications of it were discussed by the ophthalmology professor.
Besides the very open and friendly environment which encourages participants to give their feedback at the end of each course, a formal summative written and practical test for evaluating, knowledge, attitude and ability was performed.
These training courses entered the residents' curriculum in Farabi eye hospital in 2011 and have been held as annual workshops for residents.In 2015, it was decided to evaluate the effectiveness of these workshops, so 3 questionnaires were designed to evaluate the change in attitude and performance of residents.Although the optics-lab started working some years ago, this study was conducted from 2017 to 2019.
To the best of our knowledge, this is the first time such a laboratory has been designed to teach optics to ophthalmology residents.Of course, optics laboratories have been designed for other disciplines, including physics students, but there is no record of this in ophthalmology curricula emphasizing their practicality for ophthalmologists.

Research design
A quasi-experimental design with pre-posttest was used to evaluate the effectiveness of the training workshop in changing the ophthalmology residents' optical knowledge and attitude.This study adhered to the tenets of the Declaration of Helsinki.All participants were informed about the study goals and informed consent was obtained.

Research setting
The study was conducted from November 2017 to November 2019 in a designed optics lab, Farabi eye hospital, affiliated to Tehran University of Medical Sciences.Two groups of residents in the second and the third year of ophthalmology residency participated in the optics course and in this study as a component of their educational programs.

Course
This educational course was held in 4 sessions and each session was presented as three separate 10 min lectures given before start of a related series of practices based on a written curriculum.A PDF version of this curriculum was available for all residents before the sessions and a hard copy was given to each resident in the lab.
Lectures reviewed the related optical principles and their applications in practical ophthalmology to attract the attention of participants to key points.Approximately 90 min was considered for practicing the optics tests using the lab instruments.There were 6-9 residents in each class, divided into 3 groups with a fully equipped unit, and a mentor (PhD of optics).An ophthalmology professor in charge of supervising the optics and refraction course in their residency program was present in all sessions taking the responsibility of discussing the relevance of these tests to clinical ophthalmology.

The lab curriculum
The curriculum was developed by a committee of three (two optics scientists and one ophthalmologist who was in charge of optics and refraction course in the residency program of Farabi Eye Hospital), mainly based on the American Academy of Ophthalmology Clinical Optics book 1 , which is the main reference for the residents.This curriculum took advantage of the experience of the optics professors in designing a proper set up for appropriate optics tests showing the main concepts of optics principles discussed in the above mentioned reference book.
All the practical topics and exercises in the laboratory were designed in 4 main sections: Ray Optics, Optical aberrations, Wave Optics, and Electromagnetic Optics.For each section, the concepts needed by the residents were identified, then appropriate tests were designed and the application of each in the clinical work of an ophthalmologist was determined.Tables 1, 2, 3 and 4 show in detail the concepts of each section, the tests performed for them and the applications of each (Tables 1, 2, 3, 4); also, Figs. 1, 2 and 3 show some of the students' experiences in the optics lab (Figs. 1, 2, 3).

Tools of the study
Data were collected using a 3-part self-administered questionnaire, after proving its validity and reliability.
The first part included residents' demographic characteristics, such as age, gender, course and grade point average (GPA).
A 34-item questionnaire was developed to assess students' knowledge and attitudes before and after the training workshop.The questionnaire consisted of 2 parts: (1) Knowledge of the residents before and after the workshop.(2) Residents' attitude towards gaining practical knowledge in the field of optics before and after the workshop.
The knowledge part of the questionnaire concerned residents' prior knowledge of the subject and consisted of two sections: 14 questions on a 5 point Likert scale to assess self-estimation of the residents from their optical knowledge that were scored from 1 to 5; and 6 open-style questions to objectively evaluate the level of their The viewing screen is adjusted to obtain the best focus of the image.Viewing screen is moved so that the image is still clear.This distance is the depth of focus.In another experiment the object is moved so that the image is still clear.This distance is the depth of field Understanding the role of senile miosis and some optical instruments such as Kamra inlay or presbyopic IOLs in pseudo -accommodation

Depth of field and depth of focus
When the image is formed by a lens, an aperture is put on that lens, and its effect on the depth of field and depth of focus is investigated Lenses with different power are tested

Clinical application in microscope adjustment
Table 2. Optical aberrations.

Moiré method for representing aberration
The moiré fringes of the superimposed linear gratings are linear.When a grating is imaged by a lens, due to the aberrations of the lens, the image of grating is not exactly equal to the object, therefore, overlapping gratings over the image does not produce linear moiré Understanding aberration and its effect on quality of image

Spherical aberration
The viewing screen is adjusted to obtain the best focus of the image.A translucent ring is placed on the lens so that light passes only through the center of the lens.By moving the viewing screen, the best image is found in this mode.The lens power was measured.The experiment is repeated when a circular obstacle is placed on the center of the lens to let only peripheral rays pass.The lens power is measured again.The difference in image distance in these two cases is due to the lateral spherical aberration Observing different kinds of aberrations and their role on quality of image, such as night myopia, glare, halo, pincushion and barrel distortion

Coma aberration
When a perfect image is formed by a lens, the lens is rotated and tilted.Deviations in the image are due to the coma and astigmatism aberration Astigmatism aberration

Field curvature aberration
The image of a two-dimensional grid is formed by a lens, it is shown that all parts of image could not be focused simultaneously.This is due to Field curvature aberration and Distortion aberration Distortion aberration

Chromatic aberration
When the image is formed by a lens, a color filter is placed into the beam path.It can be seen that image distance is different for different colors.www.nature.com/scientificreports/knowledge and performance that were scored from 0 to 24 based on a pre-defined scoring system.The overall knowledge score was classified as 3 levels of knowledge: low, moderate and high.

Validity and reliability of the questionnaire
The validity of the questionnaire was assessed using panel of experts' method.For this purpose, the initial questionnaire was designed based on the educational objectives of the workshop and American Academy of     The simplest moiré pattern appears when two linear amplitude gratings are superimposed that have equal or nearly equal constant pitches.The pattern is the periodic distribution of reflectance or transmittance of period much larger than the gratings' pitches.The gratings could be two physical gratings or one physical grating and the image of another grating.Lenses can be tested by using the moiré technique.Using a lens, we form the image of grating in the case that, the distance between the object and screen is 4f.In this case, the grating and the image of grating are similar.By overlaying a grating similar to the first grating over the image of grating, at a small angle, we expect to see linear moiré fringes (a).But because of lens aberrations, moiré fringes are not linear.All aberrations, as well as colored aberrations, are seen simultaneously in the moiré pattern (b).If the angle is zero, we expect no moiré fringes to form, but because of the aberrations, moiré fringes are created as shown in (c).This state is the phase singularity state.

Discussion
Lecture-based teaching is the most common method for presenting up-to-date information in learning process, but it has been perceived to have low educational yield, as it fast-forwards the student from problem to solution and focuses on memorizing, ignoring the analytical way of thinking, so it promotes shallow learning.Alternative active learning models have been introduced to address these concerns.Some of these methods to stimulate student's engagement in learning process are video-based learning, group working encouragement, problem-based learnings, flipped classrooms, workshops and laboratories [2][3][4][5] .
There are advocates for active learning in clinical optics, but few studies have been conducted in this regard.Tu et al. investigated the effectiveness of flipped classroom versus lecture-based clinical optics curricula in an ophthalmology resident's education setting.They showed that flipped classroom approach to clinical optics education was associated with higher performance on the optics subsection of the Ophthalmic Knowledge Assessment Program (OKAP) examination, and they suggested that flipped classroom approach may be more effective than traditional lectures for teaching clinical optics 6 .Some innovative workshops and experienced-based approaches have been proposed in optometry curricula.Putnam has demonstrated laboratory activities and problem solving sessions in optics curriculum at the Arizona College of Optometry that aims to provide students with an understanding of geometrical, physical, and visual optics principals 7 .Faheemah Saeed described handson learning of geometric optical principles by small groups of students within the large lecture setting.She used table-top equipment (lenses, mirrors, prisms and laser sources) to increase visualization of optical principles and students' engagement in the learning process and reported that it was well-received in the majority of students.However, in this paper, only the geometrical optics was practiced and the improvement of students' performance by changing the teaching method was not studied objectively 8 .
As we believe extending the concepts learned in the classroom via lectures to the lab can facilitate the learning process of students, this lab was set up for this purpose.Its positive results have been observed from the first year.In the early years, students were evaluated practically in the lab in each session and with a written exam at the end of the course.During those years, evaluation of students' scores and feedback from students and professors showed the better effect of this type of education than lectures.From 2017, we decided to do a more objective assessment of students, so pre-posttest with a valid and reliable questionnaire was designed.The questionnaire consisted of 3 parts: questions that assessed self-estimation of the residents from their optical knowledge, openstyle questions to evaluate their knowledge and performance objectively and questions to estimate the attitude of residents towards gaining practical knowledge in the field of optics.We saw significant improvements in all 3 parts in this study.Also, in a poll at the end of the course, most of the students reported satisfaction with the workshop and tests provided in the lab in terms of usefulness of the materials and appropriateness of information.They also reported increased awareness of the importance of the optics knowledge in their practice and their willingness to implement this knowledge in their regular practice.
The strengths of this study are: (1) Contrary to the previous studies that we mentioned, in this study and in our lab, we tried to cover most of important optical issues in the field of work of an ophthalmologist with standard tests, and we did not just teach geometrical optics.( 2) Students performed all the experiments in small groups in a well-equipped laboratory.(3) An ophthalmology professor and an optics professor were both present in the lab, to demonstrate how optical concepts and their clinical applications are connected.(4) Knowledge, performance and attitude of students were evaluated with a pre-posttest study.
The limitations of our study are that our data are from a single institution, and we did not have a control group to compare our results with other teaching methods such as lecturing.However, because these students were in their second and third year of residency, they all had attended optics classes the year before, and considering the short duration of this workshop, their change in performance in this study was measured with a pre-posttest.In this study, we did not create a control group because we knew from our experiences in previous years that participating in this course would be beneficial for residents and depriving a group of students was not ethical.Therefore, we were satisfied with a before-after study.

Conclusion
The present study has addressed that training workshops and labs are effective to bring about change in knowledge and attitude of ophthalmology residents toward optics as a new teaching strategy that could be implemented in their curriculum.This was consistent with previous literatures that have reported workshops were helpful to enhance knowledge, practice and the attitude of students.So it seems that ophthalmology education can be improved by utilization of new teaching strategies.

Figure 1 .
Figure 1.Image formation by convex lens:The image of an arrow is formed by a positive lens on the observation screen.By changing the distance of the object, residents can see the place of image formation and the magnification changes.Also, by moving the lens vertically, the image moves and the prismatic effect of the lens can be observed.In addition, with this experiment, depth of field and depth of focus can be measured.

Figure 2 .
Figure 2. Single-slit diffraction pattern.In this experiment, the Wave nature of light can be shown.As the width of the slit producing a single-slit diffraction pattern is reduced, the diffraction pattern becomes wider and vice versa.

Figure 3 .
Figure 3. Observation of lens aberration by Moiré technique.The simplest moiré pattern appears when two linear amplitude gratings are superimposed that have equal or nearly equal constant pitches.The pattern is the periodic distribution of reflectance or transmittance of period much larger than the gratings' pitches.The gratings could be two physical gratings or one physical grating and the image of another grating.Lenses can be tested by using the moiré technique.Using a lens, we form the image of grating in the case that, the distance between the object and screen is 4f.In this case, the grating and the image of grating are similar.By overlaying a grating similar to the first grating over the image of grating, at a small angle, we expect to see linear moiré fringes (a).But because of lens aberrations, moiré fringes are not linear.All aberrations, as well as colored aberrations, are seen simultaneously in the moiré pattern (b).If the angle is zero, we expect no moiré fringes to form, but because of the aberrations, moiré fringes are created as shown in (c).This state is the phase singularity state.

Table 1 .
Ray optics.Refractive indexTo investigate Snell's law, we use a transparent semicircular optical flat.The device is adjusted so that light passes through the optical axis and strike the flat side of the semicircular optical flat.The incidence angle and refractive angle are measured and the refractive index is calculated by Snell's law To obtain the focal length of a negative lens, it is combined with a positive lens.Residents can experience real and virtual image formation Pin hole The resident can calculate lateral chromatic aberration by this experiment Vol:.(1234567890) Scientific Reports | (2023) 13:21844 | https://doi.org/10.1038/s41598-023-44688-1